MEE 452: Design Economy, Optimization, Reliability and Safety

[Based on: L.C. Burmeister, Elements of Thermal-Fluid System Design, Prentice Hall, 1998]

Engineering Economy: • Time value of moneyTime value of money• InflationInflation• Cost estimationCost estimation• Taxes and depreciationTaxes and depreciation• Annualized costAnnualized cost

F=P(1+I)N

System Design Optimization

• Basics: (Minimums and Maximums):(Minimums and Maximums): Lagrange multipliers, Concave & Convex programming

• First-order gradient methods ():(): Steepest descent, Conjugate gradients

• Second-order Newton’s procedure ():():

• Quadratic interpolation

min

Direction of steepest descent

System Design Optimization (2)

• Linear programming• Global Optimization Algorithms• Fuzzy system optimization ():(): • Neural networks for

optimization • Sensitivity coefficients

Design Reliability

• Probability basics• Components in combinations• Maintenance • Common-mode and other

failures • Reliability allocations• Reliability with standby

Surviving fraction of fluorescent lamps

400

100

Average lamp life [1000 hr]

% S

urvi

val

20 8060 100 120

50

99%

Design Reliability (2)

• Reliability with capacity and load distribution

• Event and fault trees• Least cost by parallel operation• General reliability-enhancing

measures

General effect of reliabilityupon system cost

optimumrepair

capitaltotal

Reliability

Cos

ts

Product Liability and Safety

• Product liability historyProduct liability history• Insurance premium and other Insurance premium and other

costscosts• Effect on innovationEffect on innovation• Codes and StandardsCodes and Standards

– Primary standards (SI, SI-Units

– Secondary/national standards: NIST, ANSI

http://www.uspto.gov/

Design for Safety

• Hazard elimination• Safety guards and enclosures• Safety warnings and instructions• Protective clothing • Administrative controls• Human safety factors• Maintenance safety

Safety Terms

• Compliance:Compliance: The minimum set of requirements by which an environment conforms to the local, state, and federal rules, regulations, and standards. A workplace may be cited by OSHA for imminent danger, serious violation, etc.

• Hazard:Hazard: A set of a system's potential and inherent characteristics, conditions, or activities which can produce adverse or harmful consequences, including injury, illness, or property damage (antonym to safety).

• Hazard analysis techniques:Hazard analysis techniques: A number of analytical methods by which the nature and causes of hazards in a product or a system are identified.

• Mechanical injuries:Mechanical injuries: A type of physical injury caused by excessive forces applied to human body components, such as cutting, crushing, and straining (ergonomic hazards).

• Risk control:Risk control: The process by which the probability, severity and exposure to hazards (per mission and unit of time) are considered to reduce the potential loss of lives and property.

• Toxic substances:Toxic substances: Those substances that may, under specific circumstances, cause injury to persons or damage to property because of reactivity, instability, spontaneous decomposition, flammability, or volatility.